1. Field of the Invention
This invention relates to a surgical instrument having pivotably interconnected levers which may be locked in their closed position by locking means, and disengaging means for releasing the locking means. Prior instruments of this kind such as tongues, hysterectomiums and the like are complicated, expensive, bulky, impractical in operation and tend to hinder and obstruct the operator.
2. Related Art
In an instrument disclosed in U.S. Pat. No. 3,393,680, a pair of levers are equipped with flat actuating plates instead of the usual ring grips, such plates being inclined relatively to the moving plane of the levers. By means of specific differing pressure by the thumb onto the one of these actuating plates, locking teeth rigidly connected to the levers may be engaged or disengaged. Besides the fact that such an instrument may not be used as easily as the instruments with the usual ring grips, it is doubtful whether proper engaging and release of the locking means is achieved.
U.S. Pat. No. 3,038,467 discloses an instrument having a locking mechanism including one part of the locking teeth pivotably mounted on the one of the levers and usually maintained in engaged position by spring force. By pressure with a finger, this part of the locking mechanism may be disengaged against the spring force. This device is bulky and hinders operation of the instrument. Another drawback resides in that the one part of the locking mechanism charged by the full locking forces has to be pivotably connected to one of the levers.
German Pat. No. 20 25 868 discloses an instrument having one of its grips mounted for relative displacement on its lever, and this grip is coupled with a part of a locking device in such a way that this part is brought or held in engagement when the instrument is closed while it is disengaged when the instrument is opened. This mechanism is very complicated, and during the clamping operation the full actuating force acting the grip is transmitted to the disengageable part having the form of a latch of the locking mechanism, whereby high friction and high water occurs.
Due to the foregoing drawbacks, none of the prior solutions has met with success in practice, and instruments which have no auxiliary means for disengaging their locking means are generally used. However, considerable force and skill is required for disengaging the locking means and accurate, sensitive operation of the instrument becomes more difficult.